This invention relates generally to surveying equipment and more particularly to surveying equipment having lightweight and yet robust, precision construction.
Surveying equipment and particularly the support structure therefore must be able to withstand all kinds of environmental conditions while retaining its integrity and dimensional accuracy. In many instances, the dimensional accuracy is imperative in order to obtain the correct measurements in a geographic survey. For instance, prism poles and global positioning satellite (GPS) poles must be able to retain a substantially fixed position of extension as they are moved from place to place over uneven terrain and in all kinds of weather. Prism poles include two or more interfitting pole sections, and support a prism or other measurement device at the top used to sight or determine positions with laser, modulated infrared, angular and/or GPS position locators or like surveying systems. The prism reflects light back to the position locator for determining the location of the prism at different locations in a survey. The prism pole may be constructed with telescoping sections so that it may be collapsed to a reduced height (e.g., about four feet) for storage and transport, and then extended to its operating height which may be, typically, eight feet or more. In topological surveys, it is important that the pole be able to maintain its extended height as it is moved from place to place. It is therefore, critical to be able to lock the pole sections in a fixed position of extension in such a way as to have them stay. Moreover, the pole must maintain its longitudinal axis as it is extended so that its extended height is accurate every time. Similarly, the pole must be able to withstand numerous cycles of extension and retraction, and frequent rough handling while maintaining this accuracy. Still further, it is frequently desirable to completely detach the telescoping sections without substantial disassembly of the surveying pole or loss of accuracy upon reassembly.
The need for durability and accuracy has traditionally led to making surveying poles out of metal. However, metal poles can expand and contract significantly with changes in the temperature of the surrounding environment which is detrimental to accuracy of the survey. Metal poles are also capable of plastic deformation which can lead to inaccurate measurements. Carrying a heavy metal pole over uneven or broken terrain, as will be frequently necessary in surveying, can be very difficult and physically taxing. Using metal poles in the outdoors also presents a risk of lightening strike. It is possible to make poles out of lighter weight, non-conducting material, such as fiberglass, which are sturdy and weather-resistant. However, these poles will typically not withstand the clamping forces conventionally applied to metal poles to hold them in a fixed extension. Lower clamping forces may not adequately hold the pole sections in position. A similar problem is present when attaching something which must maintain a precise orientation, such as a level, to the pole. Non-metal materials may also be less likely to withstand impact forces associated with forcefully retracting the pole sections.
The surveying poles or other surveying equipment support structure may have telescoping sections, screw-together sections or a combination of the two. It is important to be able to rapidly collapse the poles for storage and transport. Also for cleaning in the field, the pole sections need to be able to be quickly and accurately disassembled and reassembled. Regardless of the material of the pole, it is often difficult to economically manufacture the pole sections so that they will maintain the same linear axis every time they are screwed together. One problem is the initial installation of screw fittings in ends of the pole sections. Care must be taken to achieve axial alignment upon installation. Another problem is the accumulation of debris on the fittings so that when screwed together, the fittings do not achieve face-to-face engagement which results in axial misalignment of the pole sections. For telescopingly interfitted pole sections, it is important to be able to easily disassociate the sections for cleaning or repair, and reassemble them while maintaining accuracy.
It is also not uncommon for these poles to have some accessory equipment. For instance, the bottom of a prism pole is conventionally equipped with a steel point to locate the pole on the ground. However in circumstances where the ground is soft, it is undesirable to have the point engaging the ground because the point tends to penetrate the surface of the ground. As a result, the location of the top of the pole above the ground can be inconsistent. Conventionally, the steel point has been removed and replaced with a blunt or greatly enlarged blunt end under these circumstances. The replacement involves several steps and it is necessary to carry the blunt end (or the steel point) around separately from the pole until used. The steel point can be difficult to safely carry because its point can be rather sharp.
Among the several objects and features of the present invention may be noted the provision of a lightweight surveying pole which is sturdy and weather-resistant; the provision of such a surveying pole which accurately maintains an extended height; the provision of such a surveying pole which maintains sections in a coaxial relation; the provision of such a surveying pole which can be disassembled and accurately reassembled for cleaning and repair; the provision of such a surveying pole which can be reconfigured with minimal steps; and the provision of such a surveying pole which can be efficiently manufactured with high accuracy.
A surveying pole constructed according to the principles of the present invention generally comprises at least one pole section and a point mounted on a lower end of said one pole section for engaging the ground. A shoe sized and shaped for covering the point is formed for releasable connection of the shoe to the surveying pole over the point to selectively cover the point whereby the surveying pole is capable of selective configuration for use in terrain having different surface properties without removal of the point.
In another aspect of the invention, a surveying pole generally comprises at least one pole section and a point adapted for mounting on a lower end of said one pole section for engaging the ground, and a shoe formed for releasable connection to the surveying pole at the lower end to selectively configure the surveying pole for use in terrain having different surface properties. The surveying pole is adapted for stowing the shoe at a location away from the lower end of said one pole section when the shoe is not needed.
In a further aspect of the invention, a level vial holder for holding a level vial capable of indicating orientation of an object is adapted for mounting on the object, such as a surveying pole. Generally, the level vial holder comprises first and second holder members engageable with the object on generally opposite sides thereof, and adapted to be interconnected for clamping engagement with the object. The first and second holder members have respective engagement surfaces shaped at least partially in correspondence with the shape of an exterior surface of the object. The first holder member including the engagement surface is formed of a rigid material for positively locating the level vial holder relative to the first pole section. The second holder member has an elastomeric pad on its engagement surface for enhancing frictional resistance to movement of the level vial holder axially of the surveying pole.
In a still further aspect of the present invention, a surveying pole generally comprises at least one pole section and a point adapted for releasable mounting on a lower end of the pole section for use in locating the surveying pole on the ground. The point comprises a body, a tip formed for releasable interconnection with the body, and a spare tip formed for releasable interconnection with the body. The body has a cavity therein sized and shaped to hold the spare tip when not in use.
Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.